Compositions and methods for improving curd yield of coagulated milk products

ABSTRACT

Disclosed are compositions and methods for enhancing the yield of coagulated milk products including cheese and other fermented milk products. Admixture of structurally expanded celluloses into milk allows substantial incorporation of additional whey solids and fluids into the caseinate matrix. The resulting interactive particle network comprising the cellulosic microfibril substructure and caseinate curd is readily manipulated by standard methods employed in the dairy industry to produce a variety of natural and processed dairy products with increased yield.

Milk broadly consists of lipid, lactose and protein. The proteinfraction is comprised of two general classes—soluble lactoalbumins andthe dispersed phase micelle of casein. Casein is a remarkable protein inthat it readily undergoes coagulative denaturation under acidicconditions or by action of certain proteinases designated as rennets.The resulting curd is then manipulated to form cheeses and otherfermented milk foods.

Milk is readily fractionated into lipid and nonlipid fractions. Thelatter fraction can be dried into a shelf-stable powder designatednonfat dry milk (NFDM). Likewise the whey byproduct of cheesemanufacture is readily dried into a stable powder. Both products areused extensively as functional ingredients in many food products. Ingeneral milk and derived milk products are bought and sold on the basisof milk solids content. Most processed milk products have standards ofidentity defining the moisture and solids content. In this regard milksolids content is highly variable—for example yogurt is approximately10% solids and romano cheese approximately 77% solids. Hence yield ishighly correlated with recovered milk solids and any method thatrecovers traditionally lost milk solids into the final product couldhave substantial economic impact. In the case of cheese, whey solidsrepresent unrecovered material.

With the advent of consumer demand for reduced calorie and no fatvariants of standardized products, increased moisture incorporation toreduce caloric density and partially replace lipids is an area ofconsiderable interest. For such nonstandardized dairy products yield isstill indexed to recovered milk solids but additionally is leveraged byincreased moisture content; every additional pound of moistureincorporated into the finished product results in a net one pound gainof product. Hence yield enhancement for these products is a combinationof milk solids recovery and moisture incorporation, provided a productwith satisfactory organoleptic quality can be achieved.

For purposes of describing this invention, yield enhancement orimprovement refers to the incremental increase in the amount ofrecovered product versus a control experiment. The incremental increasewill result from a combination of additional incorporated milk solidsand moisture.

The dairy industry has long been concerned with yield improvement (seefor example “Factors Affecting the Yield of Cheese” published by theInternational Dairy Federation (Brussels, Belgium) 197p, 1991 and“Cheese Yield and Factors Affecting Its Control” IDF (Brussels, Belgium)540p, 1994). With the exception of products such as yogurt andbuttermilk where the entire milk base is conserved, substantial lossesof milk solids occur in the whey. Whey solids frequently represent aco-product liability as their cost of recovery matches or exceeds theirmarket value. A method of incorporating more whey solids into fermenteddairy products would not only enhance recovered product yield, but couldmaterially contribute to a reduction in whey discharge.

It has now been found that certain forms of cellulose designatedstructurally expanded celluloses (SEC) which are described below, havethe unexpected effect of dramatically increasing curd yield whenincorporated into skim or full fat milk. The SEC appears to becomeintimately incorporated into the caseinate gel structure early onreducing the rate and extent of syneresis characteristic of caseinatecurds. The result is that more whey and whey protein solids areincorporated into the curd structure and carried into the low pH cookingenvironment. Depending on the product, it has been found that much moremoisture is retained in mechanically dewatered curds. Insofar as isknown, it has not previously been proposed to use SEC in the art ofmaking cheese and fermented milk products.

In order to appropriately define and distinguish structurally expandedcellulose, SEC, from other forms of cellulose and hydrocolloidalpolymers and gums mentioned herein, it is necessary to briefly examinecellulose structure and methods of manipulation. For example powderedcellulose is known in the art of cheese manufacture as an anticakingagent for ground cheese products. Carboxymethyl cellulose and othercellulose ethers have been considered as useful additives to enhancetexture of low-fat skim and processed cheese products. Hencedifferentiation of SEC from other types of “cellulose” known in the artof cheese manufacture is important for distinguishing SEC from priorart.

In chemical terms cellulose specifically designates a class of plantderived linear, glucose homopolysaccharides with B 1-4 glycosyl linkage.It is the dominant structural polysaccharide found in plants and hencethe most abundant polymer known. The function of cellulose is to providethe structural basis for the supramolecular ensemble forming the primarywall of the plant cell. Differentiation and aggregation at the cellularlevel are highly correlated with cellulose biosynthesis and assembly. Incombination with lignin, heteropolysaccharides such as pectin andhemicelluloses and proteins, the cellulosic containing primary cell walldefines the shape and spatial dimensions of the plant cell. Thereforecellulose is intimately involved in tissue and organelle specializationassociated with plant derived matter. Over time the term “cellulosesubstance” or simply “cellulose” has evolved as a common commercialdescriber for numerous non-vegetative plant derived substances whoseonly commonality is that they contain large amounts of B 1-4 linkedglucan. Commercially, combinations of mechanical, hydrothermal andchemical processing have been employed to enrich or refine the B 1-4glucan content to various degrees for specific purposes. However, onlyhighly refined celluloses are useful substrates for structuralexpansion. Examples of highly refined celluloses are those employed aschemical grade pulps derived from wood or cotton linters. Other refinedcelluloses are paper grade pulps and products used in food. The latterare typically derived from nonwoody plant tissues such as stems, stalksand seed hulls.

Refined cellulose can be considered a supramolecular structure. At theprimary level of structure is the B 1-4 glucan chain. All cellulose issimilar at this level. Manipulation at this level would by necessityinvolve chemical modification such as hydrolysis or substitution on theglycosyl moiety. However, as outlined next this level of structure doesnot exist as an isolated state in other than special solvent systemswhich are able to compete with extremely favorable intermolecularenergies formed between self associating B 1-4 glucan chains.

In contrast to primary structure, a stable secondary level of structureis formed from the nascent B 1-4 glucan chains that spontaneouslyassemble into rodlike arrays or threads, which are designated themicrofibril. The number of chains involved is believed to vary from 20to 100. The dimension of the microfibril is under the control of geneticexpression and hence cellulose differentiation begins at this level.Pure mechanical manipulation is not normally practiced at this level oforganization. However, reversible chemical modification is the basis forcommercial production of reconstituted forms of cellulose fibers such asrayon. Chemical substitution by alkylation of the glycosyl moiety yieldsstable ether substituted B 1-4 glycans which no longer self assemble.This reaction forms the basis for the production of commercial forms ofcellulose ethers such as carboxymethyl (CMC), hydroxyethyl (HEC),hydroxypropyl (HPC) and methyl or ethyl (MC & EC) cellulose. One furthermodification at the secondary structural level involves intensive acidhydrolysis followed by application of high shear to produce colloidalforms of microcrystalline cellulose (MCC). This modification is bestdeferred to the next level of structure as most forms of MCC arepartially degraded microfibril aggregates.

The third level of cellulose structure is that produced by theassemblage of microfibrils into arrays and ribbon like structures toform the primary cell wall. As in the case of secondary structure,tertiary structure is under genetic control but additionally reflectscellular differentiation. It is at this level that other structuralpolymeric and oligomeric entities such as lignin and proteins areincorporated into the evolving structure. Selective hydrolyticepolymerization and removal of the non-cellulose components combinedwith application of sufficient shear results in individually dispersedcellular shells consisting of the cellulosic skeletal matrix. With theremoval of strong chemically and physically associated polymericmoieties which strengthen the cellulose motif, structural expansion bymechanical translation and translocation of substructural elements ofcellulose can begin to occur.

The process by which structural expansion occurs is that of rapidanisotropic application of mechanical shear to a dispersed phase.Particles of refined cellulose, consisting of cellular fragments,individual cells or aggregates of a few cells, are dispersed in aliquid. The continuous liquid phase serves as the energy transductionmedium and excess enthalpy reservoir. While the individual forcesmaintaining secondary and tertiary structure of the refined celluloseparticles are largely noncovalent and hence of relatively low energy,the domains of collective ensembles possess extraordinaryconfigurational stability due to the large number of interactions. Onlyby application of intense hydraulic gradients across a few microns andon a time scale that precludes or minimizes relaxation to meretranslational capture, can sufficient energy be focused on segments ofthe refined cell wall to achieve disassembly of tertiary and secondarystructure. In practice a small fraction of the applied energy iscaptured by structural expansion of the dispersed phase. The vastmajority of useful energy is lost into enthalpy of the continuous phaseand can complicate processing due to high temperature excursions. Asdisassembly progresses and the structures become smaller and selectivelymore internally ordered, disassembly rates diminish rapidly and theprocess becomes self limiting.

Three general processes are known in the art of cellulose manipulationto provide structurally expanded celluloses useful for practice of thisinvention. The simplest is structural modification from intense shearresulting from high velocity rotating surfaces such as a disk refiner orspecialized colloid mill, as described in U.S. Pat. No. 5,385,640. Asecond process is that associated with high impact discharge such asthat which occurs in high pressure homogenization devices, such as theGaulin homogenizer described in U.S. Pat. No. 4,374,702. The thirdprocess is that of high speed, wet micromilling whereby intense shear isgenerated at the collision interface between translationally acceleratedparticles, as described in U.S. Pat. No. 4,761,203. It would be expectedthat anyone skilled in the art could apply one or combinations of theabove processes to achieve structurally expanded forms of celluloseuseful in the practice of this invention.

The entire disclosures of the above-mentioned U.S. Pat. Nos. 4,374,702,4,761,203 and 5,385,640 are all incorporated by reference in the presentspecification, as if set forth herein in full.

Two other commercial modifications are commonly employed at thisstructural level and are mentioned to distinguish the resulting productfrom SECs. The first involves indiscriminate fragmentation by variousdry grinding methods to produce powdered celluloses and is widelypracticed. Such processes typically result in production of multimicrondimensional particles as intraparticle fragmentation and interparticlefusion rates become competitive in the low micron powder particle sizeregion. Typical powdered celluloses contain particle size distributionsranging from 5 to 500 microns in major dimension and may be highlyasymmetric in shape. These products are employed as anticaking or flowimprovement additives for ground and comminuted forms of cheese. Thesecond process involves strong acid hydrolysis followed by moderatedispersive shear producing colloidal microcrystalline cellulose (MCC).It is believed that certain less ordered regions comprising tertiarystructure are more susceptible to hydrolytic depolymerization thanhighly ordered domains resulting in shear susceptible fracture planes.Dispersed forms of MCC are needlelike structures roughly three orders ofmagnitude smaller than powdered celluloses and range from 5 to 500nanometers in width to longitudinal dimension, respectively. On spraydrying MCC aggregates to form hard irregular clusters of microcrystalswhose particle dimensions range from 1 to 100 microns. The resulting MCCclusters can serve as a precursor to a unique SEC best described as amicroscopic “puff ball” reported in U.S. Pat. No. 5,011,701 and isreported to be a fat mimetic. MCC also finds application as a rheologycontrol agent in processed cheese products.

Finally, the quaternary or final structural. level of cellulose is thatof the cellular aggregate and is mentioned only for completeness. Thesesubstances may be highly lignified such as woody tissue or relativelynonlignified such as those derived from the structural stalks and seedhulls of cereal grain plants. Commercial types of these materials arebasically dried forms of nonvegetative plant tissue. These moderatelyelastic substances respond to mechanical processing by deformation andultimate fracture along the principal deformation vector. Consequently,these materials readily undergo macroscopic and microscopic sizereduction and are reduced to flowable powders by conventional cutting,grinding or debridement equipment. Because of the cohesive strength ofthe molecular ensemble comprising quaternary structure, these materialsare not candidates for systematic structural expansion at the submicronlevel without chemical intervention.

Structural expansion as defined herein is a process practiced on refinedcelluloses involving mechanical manipulation to disassemble secondaryand tertiary cellulose structure. The ultimate level of expansion wouldbe to unravel the cell wall into individual microfibrils. Although plantspecific, a typical microfibril is best described as a parallel array of25 to 100 B 1,4 glucan chains with diameter in the 50 nanometer rangeand variable length ranging from submicron to micron multiples. Inpractice generation of a dispersed microfibril population is not arealistic objective and only of academic interest. What is usuallyachieved because of the relatively indiscriminate application ofmechanical energy is a highly heterogeneous population of miniaturefibrils, ribbon-like and slab-like structures. These structures displayirregular distention of individual microfibrils and aggregates ofmicrofibrils from their surfaces and at internal and externaldiscontinuities. The ensuing collage consists of an entangled andentwined network of cell wall detritus to form a particle gel. Some ofthe larger structural features with dimensions in the micron range arediscernible with the light microscope; however higher resolutiontechniques such as scanning transmission electron microscopy arenecessary for detailed observation of submicron features. This particlegel network exhibits a vast increase in surface area associated with thevolumetric expansion and projection of cell wall structure into thecontinuous phase medium. Lastly, structurally expanded celluloses usefulfor purposes of this invention may be further characterized bypossessing a water retention value greater than 350 and a settled volumeof at least 50% for a 5% w/w dispersion of said SEC in aqueous media.

It is contemplated that certain soluble hydrocolloids may be useful inpractice of the invention. Dispersive hydrocolloids such ascarboxymethylcellulose, CMC, are believed to bind to SECS throughinteraction of unsubstituted regions on the glucan backbone with the SECsurface, perhaps on the distended microfibril. The presence ofcarboxymethyl substituents imparts anionic polyelectrolyte character tothe CMC backbone and hence on its association with SEC imparts astationary negative charge to the SEC surface. This stationary charge isbelieved to help control flocculative association of SEC and perhapsenhance interaction with colloidal lipid and casein micelles. Otherassociative hydrocolloids which bind to cellulose such as glucomannans(for example guar gum) help to control water mobility. Colloids, such asMCC, and hydrocolloids, such as xanthan and gellan gums are SECinteractive and assist in fine tuning gel structure for thecolloidal-network caseinate system. Locust bean gum, konjac gum, pectinand the like may also be used for this purpose.

The effect of SEC on curd yield is dramatic, particularly when used inthe range from about 0.05% to about 0.5%, based on the weight of themilk with which it is admixed. For example the incorporation of SEC atlevels of 0.1° w/w based on fluid milk result in significant yieldimprovements two orders of magnitude greater than the incrementalpercent of SEC solids. The incorporation of SEC into fluid milk isreadily achieved using both dried and prehydrated paste forms. Thefollowing examples are illustrative for practice of the invention by onenormally skilled in the art and are not intended to limit its scope.

DESCRIPTION OF THE INVENTION AND EXAMPLES

Two methods for characterizing SEC are useful for purposes of practicingthis invention. The first is a simple settled volume test. A powdered orprehydrated SEC is fully dispersed at a specified mass into a specifiedvolume of water. The apparatus usually employed to measure settledvolume is the graduated cylinder. The dispersed cellulose phase isallowed to gravity settle to a constant bed volume (usually 24 hr) whichto a first approximation reflects the specific dispersed phase volume ordegree of structural expansion. SEC useful for practicing this inventionis characterized by gravity settled volumes of at least 50% for a 55 w/waqueous suspension of cellulose. For example a 51 w/w suspension ofpowdered celluloses characterized as 200 mesh from cottonseed (BVF-200,International Filler Corporation, North Tonawanda, N.Y.), refined woodpulp (BW-200, Fiber Sales & Development Corporation, St. Louis, Mo.) andrefined soy hulls (FI-1, Fibred Inc., Cumberland, Md.) yield settledvolumes of 31.2%, 23.2% and 22.4%, respectively in 24 hr. These forms ofcellulose while potential precursors for SEC are readily distinguishedfrom SEC by this test. A second method of characterization involvesviscometry. SEC begins to form volumetrically sustainable, continuousparticle gels at concentrations in the vicinity of 0.5% w/w in theabsence of other dispersed substances. This critical concentration maybe significantly reduced in the presence of other dispersed colloidalmatter. The onset of formation of the particle gel and the gel strengthare characteristic of the type of SEC and the degree of structuralexpansion. Typically, the particle gels exhibit well behaved, reversiblepseudoplastic behavior in the 15 to 3% w/w concentration range. Thisbehavior can be modeled by the power law using a rotational viscometersuch as the Brookfield DVIII, a programmable rheometer (BrookfieldEngineering Laboratories, Inc., Stoughton, Mass.). A log/log plot of theshear rate versus shear stress at a specified concentration gives twocharacteristic system parameters: the flow index and consistency index.The consistency index is reflective of intrinsic gel strength (restingstate extrapolation) and the flow index which is indicative of thedegree of pseudoplasticity or dynamic particle/particle shear dependentinteractivity. SECS useful for the practice of this invention arepreferably characterized by displaying pseudoplastic behavior which ismodeled by the power law. In the range of 1-2% w/w at 20 deg. C. thepreferred SECS display flow indexes less than unity and typically in therange of 0.2 to 0.7. The preferred consistency indexes typically rangefrom 500 to 10,000 cp.

In the following examples, actually fermented cheese products are madein the usual way with the improvement that SEC is dispersed in milk atthe beginning of the process. Thereafter, the appropriate culture isadded to the milk which is then allowed to ferment for the prescribedtime, depending on the type of cheese, to establish a robust culture. Acoagulant, e.g., rennet, is added or not, as the case may be. Thecoagulum is cut into pieces and then subjected to conditions causingwater to be expressed from the coagulum, which may be gravity draining,melting/agglomeration or mechanical pressing, it can again depending onthe type of cheese.

Example 1 Skim Milk Curd

Four gallons of pasteurized skim milk were equilibrated at roomtemperature and pooled. The pooled milk contained 8.09% nonvolatilesolids (104° C. oven to constant weight, typically 24 hr.). For each offour experiments a 3500 portion was microwaved to reach a temperature of88° F. A never dried paste concentrate of SEC from refined cotton seedlinters (CS-SEC) was prepared as described in U.S. Pat. No. 5,385,640.The experiments were conducted at CS-SEC concentrations of 0.00, 0.11,0.17, and 0.22% w/w. The solids content of the paste was 6.66% on an “asis” basis and the power law characterization parameters were 0.35 and4838 cp for the flow index and consistency index, respectively,determined for a 1.5% w/w aqueous dispersion at 20° C. The indicatedamounts paste form of the CS-SEC was initially mixed with sufficientmilk to give a volume of 500 ml and dispersed into the milk by means ofa rotor/stater dispersator (Omni Mixer ES, Omni International,Gainesville, Va.) operating with a 35 mm generator at 6000 rpm for 3minutes. After dispersing the CS-SEC, it was added to the remainder ofthe milk plus any additional water and mixed on the dispersator assemblyfor 3 minutes at 8000 rpm. The active culture was added two minutes intothe mixing process. The culture employed was a freeze dried, mesophiliclactic culture (R707Chr. Hansen, Inc., Milwaukee, Wis.). It was a directvat culture (DVC) used at 1 unit/gal of milk. The culture was preparedby addition of 1.54 g lyophilized powder to 120 g skim milk. After 15minutes hydration, the culture was dispersed by means of a small handheld dispersator (Omni 1000, Omni International) operating a 10 mmgenerator for 1 min at 10000 rpm. A 25 g aliquot of the culture solutionwas used for each 3500 g (approximate one gallon) milk experiment. Thecomposition of each experiment is summarized in TABLE 1.

TABLE 1 skim CS-SEC culture milk paste water mixture #1 3500 g 0 120 g 25 g #2 3500 g 60 g 60 g 25 g #3 3500 g 90 g 30 g 25 g #4 3500 g 120 g 0 25 g

The mixtures were placed in a circulated air oven to incubate at 88 deg.F. (31 deg. C.). After one hour 0.25 ml of microbial chymosin (ChymaxII, 50000 MCU/ml, Chr. Hansen, Inc.) was added to each and theincubation continued until the pH reached 4.6 (approximately 6 hours).The curds were cut and allowed to relax for 15 minutes. The followingsequence of heating by microwave and gentle mixing was initiated to cookthe curds. Each container containing the cut curds was first microwavedto reach a temperature of 107 deg. F. and placed in a circulated airoven at 130 deg F. After one hour the containers and contents weremicrowaved again to 125 deg F. and reincubated. After another 1.5 hourthe containers and contents were microwaved to 130 deg F. andreincubated. Finally, after one hour the containers and contents weremicrowaved to 147 deg F. This ramped sequence of temperature increasesrepresents a convenient laboratory scale, curd cooking protocol. Afterone hour the cooked curd was drained using a cheese cloth lined colanderat room temperature for 12 hours. The mass of recovered curd and wheywas recorded and the nonvolatile solids of each fraction determined (104deg C. to constant weight). The mass balance results are summarized inTABLE 2.

TABLE 2 Starting whey curd final % solids* solids solids solids recovery#1 283.2 g 189.7 g 113.4 g 303.1 g 107% #2 287.2 g 175.3 g 124.8 g 300.1g 104% #3 289.2 172.8 g 126.8 g 299.6 g 104% #4 291.2 177.2 g 135.4 g312.6 g 107% *milk solids @ 8.09% × 3500 g + CS-SEC solids

The mass balance appears self consistent from the above data. TABLE 3summarizes the key yield parameters.

TABLE 3 % recovery of solids curd net yield of curd solids based onstarting solids versus control #1 40.0% — #2 43.4% 8.5% #3 44.1% 10.0%#4 46.5% 16.2%

It is clear that small amounts of CS-SEC impart relatively largesystematic yield increases in curd yield as a function of increasingconcentration.

Example 2 Cottage Cheese

Cottage cheese represents a fermented cheese product with the simplestcurd processing. Basically, the cut, cooked curd is washed, salted andat the option of the processor remixed with a cream based dressing. Asimilar procedure to EXAMPLE 1 was used for curd production with theexception that a mixed frozen culture was used. One gram of frozencultures LB-12 and St-C-5 (Chr. Hansen, Inc., Milwaukee, Wis.)representing thermophilic lactic cultures Lactobacillus andStreptococcus, respectively, were dispersed into 105 g of skim milkaccording to the protocol of EXAMPLE 1. The skim milk was not pooled,but each gallon possessed the same production time stamp and the averagesolids content was 8.25%. The composition of each experiment issummarized in TABLE 4.

TABLE 4 Skim CS-SEC milk Water paste #1 3836 g 80 g 0 #2 3845 g 40 g 40g #3 3842 g 60 g 20 g #4 3851 g 80 g 0

After final cooking of the curd was complete, the curds were thensuspended in two liters of cold water and gravity drained in acheesecloth lined colander for 16 hours under refrigerated conditions.The drained curds were salted at 1% w/w. The results are summarizedbelow in TABLE 5.

TABLE 5 First Wash Final Curd salt % % weight weight yield addn solidsyield #1 663.4 g 588.0 g 100% 5.9 g 15.8 100 #2 783.3 g 684.8 g 117% 6.8g 14.9 110 #3 1111.0 721.5 g 123% 7.2 g 14.7 114 #4 1233.8 733.0 g 124%7.3 g 14.9 117

It is seen that the curd yield which represents both additional waterand solids capture slightly exceeds the recovered solids yield of theright hand column. A major yield improvement arises from the firstincrement of CS-SEC representing 0.1% w/w CS-SEC solids.

Example 3 Mozzarella Cheese

Mozzarella cheese represents a form of cheese in which the cooked curdis thermally melted and dewatered in situ. The coalesced curd mass isformed into a ball and incubated in a saturated brine solution. A 3700 galiquot of pasteurized skim milk at 8.14% nonvolatile solids wasequilibrated to room temperature (66 deg. F.). The control contained 60g water plus 25 g of mixed culture and the test contained 60 g of theCS-SEC paste plus 25 g mixed culture solution described in EXAMPLE 2.The mixing, incubation and coagulation protocols were the same as inEXAMPLE 1 except the temperature was 92 deg. F. (33.5 deg C.). Aftercutting the curd the cut curd mixture was heated to 110 deg. F. (33.5deg. C.) using a microwave oven. After 1 hour the whey was drained tothe level of the curd and the incubation continued at 110 deg F. untilthe pH reached 5.2. The curd was then drained and washed once with 1liter of water. Salt was added at 0.75% w/w based on curd weight and thecurd was immersed in 2 liters of water at 160 deg. F. The melting andcoalescing curds were pressed into a coherent mass by means of a largewooden spoon. The curd mass was formed into a ball within a cheese clothshroud and incubated in a saturated salt brine for 2 hours. The resultsof the experiment are summarized in TABLE 6.

TABLE 6 Skim CS-SEC Water Final Cheese % % solids yield weight weightweight yield solids recovered #1 3700 g - 0 - 60 g 239.8 g 100% 46.436.9 #2 3700 g 60 g - 0 - 275.2 g 115   39.6 36.2

The results indicate that the yield of skim milk solids remained aboutthe same and that the yield increase was largely due to additional waterincorporation.

Example 4 Cheddar Cheese

Cheddar cheese represents a mechanically dewatered curd which is pressformed into a wheel or plug shape, peripherally sealed and subsequentlyaged. During the latter process it undergoes an aging and fermentativedevelopment to develop a unique flavor profile. The yield of the cheesehowever is set prior to the aging process.

For the experiment described below a specialized pneumatic press wasconstructed to run four simultaneous experiments. It consisted of fourparallel mounted pneumatic air cylinders each possessing an internaldrive cylinder diameter of 2.5 inches. The drive rod was connected to aClevis adaptor attached to a 4.5 inch diameter plastic driver enclosedwithin a 4.6 inch diameter cylindrical press housing. Holes in the sidesof the housing were drilled to allow vertical drainage of the expressedwhey. The bottom segment of the cylinder contained an elevated butstructurally supported coarse lattice platform for bottom drainage. Theassembly was pressurized by means of a nitrogen gas tank and thepressure regulated with a two stage diaphragm regulator. Typically thepress cylinder was lined with nylon cheese cloth. A 4.25 inch circular60 mesh stainless steel screen was employed as a retaining barrier andfor support of the liner against the lattice base. The curd mass to bepressed was packed into the lined cylinder and the cheese cloth linercarefully folded over the top of the packed curd. A second 60 meshstainless steel circular screen segment was placed on top and the driveassembly manually positioned in place. The volumetric compression ofcheeses in the experiments to be described were not limited by molddesign stops as are commercial presses. This allows unrestrictedcompression which is limited only by the compressibility or intrinsicwater holding capacity of the curds in question. This provides a measureof the true cheese yield at equivalent compressive equilibriumconditions for an experimental set in which one or more parameters aresystematically varied. Commercial yields would be in excess of thosereported here due to much greater water retention associated withcontrolled volumetric compression.

Pasteurized skim milk with a nonvolatile solids content of 8.40% w/w wasused. CS-SEC past and BVF-200 (a powdered cotton seed cellulose) wereidentified and sourced previously. The culture used was the lyophilizedlactic acid preparation R707 identified previously and used at 1.5 g per3800 g skim milk. It was suspended in 100 ml of the skim milk andallowed to hydrate for 15 min. at which time it was dispersed by use ofthe Omni 1000 operating at 10000 rpm, 10 mm generator for 1 min. Thepredispersion of CS-SEC and BVF-200 prior to incorporation into the skimmilk base was similar to that described in EXAMPLE 1. The skim milk basewas preheated to 90 deg F. prior to admixing with the other components.The culture was added in sequence also described in EXAMPLE 1. Thecomposition of the experimental set is summarized in TABLE 7.

TABLE 7 Skim CS-SEC BVF-200 Culture milk Water paste fiber solution #13800 g 120 g 0 0 100 g #2 3800 g 0 120 g 0 100 g #3 3800 g 112 g 0  8 g100 g #4 3800 g 104 g 0 16 g 100 g

The primary fermentation was run for 1 hr at 90° F. A 0.7 ml aliquot ofChymax II was added and the coagulation allowed to occur for 1 hr. Thecurd was cut and allowed to heal for 15 min. at which time thetemperature was raised to 100° F. by microwave treatment. The whey wasdrained by decantation and cheddaring started in a 100° F. circulatingair oven. The curds were turned approximately every 15 minutes. Aftertwo hours the curd mass was shredded and salted (8 g) and incubated 15min before moving to the press stage. The pressing sequence was 10 min @10 psi, rotate the press cake, 10 min @ 10 psi and rotate the press cakeand 8 hr @ 40 psi. Note: the pressure reflects primary cylinder pressurewhereby the actual pressure at the press cake is 0.55 of the cylinderdischarge pressure. The pressed cake was unloaded from the pressassembly and encompassing cheese cloth, blotted and weighed. The pressedcheese cakes were then air dried for 48 hr on a cutting board, turningthe cheese piece approximately every 12 hr. After drying the individualcheese pieces were enrobed with wax and stored at 34-40° F. to age. Atthe time of this disclosure the cheeses were 5 months into their agingprocess. No organoleptic or moisture analyses have been performed onthese cheeses to date and await the 12 month aging stage anniversary.The results of the experiment are summarized in TABLE 8.

TABLE 8 Curd Pressed Yield CS-SEC BVF-200 weight weight % DB wt DB wt #1290.8 g 232.9 g 100% 0 0 #2 517.0 g 312.4 g 133% 8 g 0 #3 325.6 g 254.8g 109% 0  8 g #4 353.5 g 249.2 g 107% 0 16 g

The results show a substantial improvement in the exhaustively pressedcheese product for the CS-SEC at 0.2% w/w. The increased yields for thepowdered cellulose were marginal at twice the concentration. Lastly, thepressed cheese based on SEC was uniform while the powdered cellulosecontaining cheeses were mottled and indicative of clumped aggregates ofcellulose. These clumps presumably were the result of settling of thepowdered cellulose particles to the bottom of the container duringcoagulation and continued segregation during shredding, subsequentmixing and pressing.

Example 5 Cheddar Cheese

In this example another form of cellulose is compared to SEC.Microcrystalline cellulose (MCC) has been described earlier and acommercially redispersible form CL-611 (FMC Corp., Philadelphia, Pa.)was used as a comparison. MCC is not considered an SEC but is acolloidally dispersible form of cellulose that forms particle gels inthe presence of CMC, albeit at higher concentrations than SEC. Thepurpose of this experiment was to show that SEC is much more effectivethan MCC in the production of enhanced yields of cheddar cheese. Theprotocol of EXAMPLE 5 was employed with the same skim milk solids. MCCCl-611 was used at the same concentrations as BVF-200 of the priorexample. TABLE 9 summarizes the results.

TABLE 9 Curd Pressed Yield CS-SEC MCC weight weight % DB wt DB wt #1322.6 g 254.9 g 100% 0 0 #2 468.4 g 304.5 g 119% 8 g 0 #3 340.9 g 271.0g 106% 0  8 g #4 366.6 g 264.0 g 104% 0 16 gThe results show that MCC at twice the concentration of SEC does notsubstantially improve pressed weight yield of cheddar.

Example 6 Processed Cheese

It is anticipated that SEC's will find extensive use in processedcheeses in addition to their use in naturally fermented cheeses. Thesame interactions of SEC with the caseinate microcell that have beendemonstrated to occur when premixed with milk and subsequentlycoagulated are expected to be found in the case of admixture withprecoagulated caseinates such as regular cheese melts and isolatedsodium or calcium caesinates.

What is claimed is:
 1. A composition for the production of enhancedyield coagulated milk products, said composition being in the form of adispersion consisting essentially of milk and at least one structurallyexpanded cellulose (SEC), the amount of SEC solids in said dispersionbeing from about 0.05% to about 0.5%, based on the weight of said milk,said composition being effective to increase curd yield in a coagulatedmilk product that results upon inoculation of said composition with aculture that produces said product, said increase being in the range of8.5% to 33%, compared to the same coagulated milk product that does notinclude said SEV/comprising milk and at least one structurally expandedcellulose.
 2. A composition as claimed in claim 1, containing from about0.05% to about 0.5% of said at least one structurally expandedcellulose, based on the weight of the milk component of saidcomposition.
 3. A composition as claimed in claim 1, further comprisingat least one hydrocolloid, selected from the group consisting of xanthangum, guar gum, locust bean gum, carboxymethyl cellulose, gelan gum,konjac gum or pectin.
 4. A composition as claimed in claim 1, furthercomprising at least one other physical form of cellulose.
 5. Acomposition as claimed in claim 4, wherein said at least one otherphysical form of cellulose is microcrystalline cellulose.
 6. Acomposition as claimed in claim 4, wherein said at least one otherphysical form of cellulose is powdered cellulose.
 7. A composition asclaimed in claim 1, further comprising a chemically-modified cellulose.8. A composition as claimed in claim 7, wherein said chemically-modifiedcellulose is at least one selected from the group consisting ofhydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose orethyl cellulose.
 9. A composition as claimed in claim 1, furthercomprising β1-4 glucans.
 10. A composition as claimed in claim 1,wherein said milk component is full fat milk.
 11. A composition asclaimed in claim 1, wherein said milk component is skim milk.